Underdog is a dog who has served as mascot to National Accident Helpline since 2010.
He is voiced by Joe Pasquale.
Underdog is a medium brown dog who has a bandaged arm, leg and ear (though in earlier adverts, there were three different dogs; a dark brown dog with a broken leg, a cream dog wearing a neck brace and an orange dog was a broken arm). Underdog is seen asking for compensation for the accident they had to an unseen person (voiced by Brian Blessed). After he is refused compensation, Underdog declares that he will go to National Accident Helpline. Blessed's character will act in surprise at this and/or try convince not to go through with it, only for Underdog to refuse.
- Underdog was created by Aardman Animations, who are most well known for creating Wallace and Gromit.
- Underdog's design is similar to the characters in Rex the Runt, which was also created by Aardman Animations.